from The Century Dictionary and Cyclopedia

Of high grade or quality; eminent; great; elevated: applied to persons and feelings.

Synonyms Conspicuous, extraordinary.

n. Sign; token; indication.

n. A conventional or intelligible sign designed for information or guidance; an object displayed, a motion made, a light shown, a sound given out, or the like, for direction to or communication with a person or persons (especially at a distance) apprised of or able to recognize its intended meaning: as, to hoist, sound, or make a signal; military and naval signals; a warning signal; a book of signals (see signal-book).

n. An inciting action or movement; an exciting cause; an initial impulse: as, this tyrannous act was the signal for insurrection.

To mark with a sign.

To communicate or make known by a signal or by signals: as, to signal orders; a vessel signals its arrival.

To make signals to: as, the vessel signaled the forts.

To he a sign or omen.

To give a signal or signals; make communication by signals.

n.

n. In whist, any method of showing that the player wants trumps led. See trumps signal.

n. an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes

adj. notably out of the ordinary

v. communicate silently and non-verbally by signals or signs

n. any nonverbal action or gesture that encodes a message

Etymologies

Middle English, from Old French, from Medieval Latin signāle, from neuter of Late Latin signālis, of a sign, from Latin signum, sign; see sign.

(American Heritage® Dictionary of the English Language, Fourth Edition)

From Old French segnal, seignal or Medieval Latin signāle, noun use of the neuter of Late Latin signālis, from Latin signum. (Wiktionary)

Examples

This became a spam signal because it is so easy to create large database driven websites, but in the case of many sites it is also a good * quality signal* because the site may be very info rich, covering basically every mile of the Oregon Coast Highway 101 in good, objective detail.

The issue is not really “signaling”: everybody knows that the FDIC guarantee makes your (fractional reserve) bank account safer; there is no need to *signal* the fact (signaling is necessary only in the absence of a government guarantee, and even then it’s impossible to signal *that the government guarantees your account*, since it doesn’t).

The two giants of the net are at war now over what I call signal generation: the ability to get us to generate data about ourselves—who we are, where we are, what we like, whom we like, what we buy, what we want, what we know, what we want to know—so they can serve us more relevant and valuable content, services, and advertising.

The two giants of the net are at war over what I call signal generation: the ability to get us to generate data about ourselves – who we are, where we are, what we like, whom we like, what we buy, what we want, what we know, what we want to know – so they can serve us more relevant and valuable content, services, and advertising.

If you are admitting that an important part of the signal is a social signal, then there's no way for an entrepreneur to compete on price - When you're dealing with social cues of affluence, the price tag is an key part of the signal.